The long term goal of this project is to determine systematically the relationships between (a) injection site used for low-dose heparin therapy and partial thromboplastin time (ptt) level and (b) injection site used and ecchymosis. Knowledge gained from this research will be used to develop a nursing procedure for the administration of low-dose heparin. The aim of the proposed study, therefore, is to evaluate three subcutaneous sites (abdomen, thigh, and arm) for injection of low-dose heparin. The study will be conducted at a 366 bed tertiary care medical center in Sayre, PA. A pre-treatment ptt blood test will be drawn per standard physician protocol to detect any abnormalities in patients' clotting times. Anyone with an abnormal ptt prior to initiation of heparin therapy will be excluded from the study. Subjects will be 108 inpatients who are over 18 years of age. They will have a written physician's order for low-dose heparin therapy and will be assigned randomly to one of three groups: (1) Group A - Abdominal Site; (2) Group B - Thigh, and (3) Group C - Arm. Patients in each group will receive three injections (dosage and frequency according to physician's order), with nurses using a standardized technique. Although heparin therapy may continue for a longer period of time, depending on physician orders, patients will be considered as participants in the study for the first three injections only. A second ptt will be drawn four hours after the initial heparin dose to monitor for expected prolongation in clotting times. Ecchymotic areas at all injection sites will be measured 48 hours after the third injection. In order to test the hypotheses that no difference exists among the means of the three groups with respect to the extent of ptt levels and ecchymosis, data will be analyzed by means of a one way analysis of variance (ANOVA). The significance of this study lies in the potential for providing research evidence to support nursing practice.